1. Field of the Invention
This invention relates to footwear construction. More particularly, this invention relates to the configuration of lugs of an outsole for footwear to provide improved cushioning and stability characteristics.
2. Description of Related Art
Due to an increase in the popularity of exercise, as well as everyday walking and standing, there is a need to alleviate and relieve stress on a person's feet and legs. It is important that shoes and other footwear, such as sandals, provide adequate shock absorption and stability. Moreover, it is important to have a shoe construction that accommodates the gait cycle of the individual wearer for the particular activity being engaged in.
Typically, it is the midsole of the shoe that provides the cushioning and stability to the foot of a wearer. In a conventional shoe, either polyurethane foam, EVA (ethyl vinyl acetate) foam or perhaps HYTREL foam is used as the material which provides most of the cushioning of the shoe (HYTREL is a trademark of DuPont du Numeurs & Co.). Other materials used for cushioning in the midsole include fluid filled bags.
In contrast, the outsole of a shoe and, in particular, the outsole of an athletic shoe is viewed as a necessary liability with respect to cushioning. Typically, the function of the outsole is to provide an abrasive resistant material for contacting the ground. This material, typically rubber, is heavy and provides minimal cushioning.
In the late 1970's, a shoe was developed which, for the first time, utilized the outsole of an athletic shoe to provide significant cushioning and stability to the foot of a wearer. This shoe, described in U.S. Pat. No. 4,372,058 to Stubblefield, features an outsole for a shoe designed to reduce stress on a person's feet and legs. The outsole is provided with outwardly disposed flexible lugs inclined at an obtuse angle to the lower surface of the shoe sole. This angular configuration allows the lugs to spread outwardly upon impact with the ground and thereby dissipate impact forces away from the foot and leg of the wearer. Although this shoe provides shock absorption, the need for improved shock absorption is incessant in the footwear industry.
Accordingly, one object of the invention is to provide an athletic shoe having improved shock absorption and stability.
Another object of the invention is to have the ability to vary the characteristics of the shoe sole so that the shoe can accommodate different types of use, as well as different amounts of support in different areas of a single shoe.
Another object of the invention is to provide a sole that is recyclable.
Another object of the invention is to provide means by which a strap can be used to help support the arch of the wearer or the entire foot.